Optical instrument.



PATENTED NOV. 19, 1907.

E. O. BRIDGE.

OPTICAL INSTRUMENT.

APPLICATION FILED API'LZG. 1907.

a x AQW AWV 2X m cows EPHRAIM C..BRIDGE, OF CHARITON, IOWA.

OPTICAL INSTRUMENT.

Specification of Letters Patent.

Patented Nov. 19,1907.

Application filed April 26. 1907. Serial No. 370.476.

To all whom it may concern:

Be it known that I, EPHRAIM C. BRIDGE, a citizen of the United States residing at Chariton,-in the county of Lucas and State of Iowa, have invented certain new and useful Improvements in Optical Instruments, of which the following is a specification.

My invention relates to certain new and useful im' rovements in optical instruments,

and the o ject of my invention is to produce T an instrument which is cheap to construct,

is, composed of few parts,'and one with which a "variety of work in connection with testing and treating the eyesmay be carried on.

With these: objects in view, my invention consists in certain constructions, combina tions and arrangement of arts, the preferred form of which will be rst described in connection with the accompanying drawings, and then the invention particularly pointed out in the claims.

Referring to the drawings wherein the same part is designated by the same refer j enoe numeral wherever it occurs, Figure 1 is a perspective view ofthe preferred form of my invention; Fig? 2 is a front view thereof; Fig. 3 isa cross-section.

.1 designates a hood having its rear side closed by the plate 2, provided with aper-' tures 3'. j

4 designates the beam on which is provided scales 5 and 5, the scale 5 being aid off in accordance with the strength of the 8 designates a pair'o blocks mounted to i slidein the ways 7, each of these blocks be ing provided with a central perforation ;.9. The rear face of these blocks is provided with ade ression 10 in which 1s mounted a rismatic spherical lens 1 1 the base of the prisms of the lenses being located toward each other. Mounted on the inner side of each of. the

blocksi's 9. lug 12 provided with a threaded hand screw threads which engage the threaded openings of the lugs whereby by-turning the rod the blocks carrying the lenses maybe v moved to orfrom each other.

15 area pair of slits cut in the top ot the hood and 16 are a air of pins extending up from the upper si e of the blocks 8 in line with the central axes of the lensesf By means of these pins the axes of the lenses can be located in line with the center of the pupils of the eyes of the patient to be treated;

17 are a pair of ground glasses mounted in suitable frames 18 which are pivoted at 19 to the back of the plate 2, whereby the ground glasses can be moved around to cover either 0 ening 3 in order to treat or test the eyes of t e patient separately.

In the operation of my device, the patient is first requested to look over the top of the hood, and then by turning the button 14 the pins 15 are brought just inside of the center of the pupils of the eyes. This will give the operator the pupilary distance of the pa.

tients eyes and set the lenses the properdistance apart. Areadin card of the ordinary type isnow placed int e slide with the slide pushed u to No. 0 on the scale on top of the beam. the patient can read the card at this distance he. has normal vision. The test after being made for both eyes should be made for each eye singly by turning down the ground glass covers in the ordinary manner. If the patient, however, does not read clearly whenthe slide is at 0 on the scale, then the slide is slowly drawn in until the card can be read clearly. The scale on the side of the bar then shows the number of the lens that is required to correct the vision.

To test for astigmatism, both corneal and lenticular, an ordinary astigmaticcard is placed in the slide, and the slide set at .the point on the scale where the patient was able to read the reading card. If now the lines all look alike to the patient there is no astigmatism. If however some of the lines are darker than the others,then the darker line shows the Bert meridian of the cylinder. By now moving the card carrying slide towards the eyes of the patient until all the lines look alike, the strength of the cylinder can be determined. When it is desired to exercise the muscles of the eyes of the patient,'he is requested to look through the instrument and then the lenses move alternately further apart and closer together,

-From' the above description of the construction and operation it will be seen that I l have produced a construction .Which is simple, cheap and not liable to get out of order, and one which has a wide range of use in optical Work.

What I claim as new and, desire to secure by Letters Patent is carrying a slide adapted to support testing cards, a scale'on the beam arranged in accordance with the strength of the lenses, and a second scale on the sideof the beam arranged in accordance with the strengthof lens necessary tocorrect the patients vision.

sauce 2. An optical instrument comprising a hood, 9; pair of blocks mounted in the front of" the hood, a pair of prismatic spherical lenses mounted in the blocks, a rod provided with right and left hand screw threaded portions mounted in the hood and adapt-'- ed to. engage correspondingly screw threaded portions on the blocks, one end of said rod extending through the hood and provided with a turning button whereby by the turning of the rod the blocks carrying the lenses may be moved toward and away from each other, the WhOlGOOIISLitUtiIlg a means whereby'the muscles'of the eyes of a. patient may be exercised.

In testimony whereof I afiix my signature in presence of two Witnesses.

. EPHRAIM C. BRIDGE.

Witnesses: l

PETER E. VAIL, LESTER F. SMITH. 

